Combine the egg, sour cream, Worcestershire, Old Bay, salt, onion, and parsley in a medium bowl and mix well. Add the tuna, breaking apart any large chunks, and panko; gently fold mixture together until just combined.
Using your hands, shape into patties and place on a parchment paper or foil lined baking sheet. Cover and refrigerate at least 1 hour.
Heat oil in a large non-stick skillet or a large griddle set over medium heat. Once oil is hot and shimmers (just below the smoking point), carefully place the patties one at a time in the pan, being careful not to overcrowd the pan. Cook patties until they are golden brown on the first side, about 3 to 5 minutes. Carefully flip cakes and fry on other side until golden brown, about 4 minutes. Remove the patties from the oil once they are golden brown on each side. Fry up any additional patties, adding oil between each cake as necessary.
Serve immediately with comeback sauce, tartar sauce, or simply by themselves.
Notes
Makes 4 large main dish cakes or 6 smaller appetizer cakes